Process for producing image fiber

Abstract

A process for producing an image fiber comprising drawing an image fiber preform consisting of a bundle of a plurality of optical fibers each of which is drawn from an optical fiber preform and consists of a core and a cladding, in which at least one of the optical fiber preform, the optical fiber, the image fiber preform and the image fiber is hydrogenated at a temperature higher than a room temperature, the image fiber produced having improved attenuation which is less increased when it is irradiated, particularly with gamma-ray.

What is claimed is: 
     
       1. A process for producing an image fiber comprising drawing an image fiber preform consisting of a bundle of a plurality of optical fibers each of which is drawn from an optical fiber preform and consists of a core and a cladding, in which at least one of the optical fiber preform, the optical fiber, the image fiber preform and the image fiber is hydrogenated at a temperature higher than a room temperature in a gas containing hydrogen at a partial pressure of at least 0.05 atmosphere. 
     
     
       2. A process according to claim 1, wherein the optical fiber preform is hydrogenated. 
     
     
       3. A process according to claim 1, wherein the optical fiber is hydrogenated. 
     
     
       4. A process according to claim 1, wherein the image fiber preform is hydrogenated. 
     
     
       5. A process according to claim 1, wherein the image fiber is hydrogenated. 
     
     
       6. A process according to claim 1, wherein all of the optical fiber preform, the optical fiber, the image fiber preform and the image fiber are hydrogenated. 
     
     
       7. A process according to claim 1, wherein the hydrogenation is carried out in pure hydrogen gas. 
     
     
       8. A process according to claim 1, wherein the hydrogenation is carried out in air containing hydrogen at a partial pressure of at least 0.05 atm. 
     
     
       9. A process according to claim 1, wherein the hydrogenation temperature is lower than 1,600° C.